Blast burner tip



Oct. 27, 1970 c. R. LAKE 3,536,429

BLAST BURNER TIP Filed Aug. 5, 1968 I NVEN TOR. CHARLES R. LAKE BY MW, 744%, g M,

ATTORNEYS United States Patent Oifice 3,536,429 Patented Oct. 27, 1970 3,536,429 BLAST BURNER TIP Charles R. Lake, Brecksville, Ohio, assignor to Pyronics, Inc., Cleveland, Ohio Filed Aug. 5, 1968, Ser. No. 750,136 Int. Cl. F23d 15/02 US. Cl. 431-353 5 Claims ABSTRACT OF THE DISCLOSURE A blast burner tip including a body having an inwardly extending generally cylindrical bore terminating in a transversely extending end wall and defining a combustion chamber. A plurality of relatively uniformly spaced gas-air mixture inlet ports extends through the endwall in a generally circular layout. Each of the ports is outwardly inclined relative to the axis of the bore to direct gas-air mixture into impinging relationship with the walls of the bore. The relationship of the gas-air mixture inlet ports to the chamber and certain dimensional relationships produce aspiration of air centrally and peripherally of the flame.

The present invention is directed toward the gas burner art and, more particularly, to an improved blast burner tip.

The invention will be described with particular reference to its use in shell molding machines; however, it will be appreciated that it is capable of much broader application and could be utilized in a variety of heating applications.

In the process of forming shell molds, blast burners are generally utilized for heating the formed molds. In general, the blast burners have comprised a relatively small diameter burner tip shell having one'end open and the other end closed by a perforated wall or orifice plate. The tip. shell is directly connected to a gas-air mixture supply pipe or manifold and the mixture passed through the perforated wall into the shell. Additional ambient air is aspirated into the mixture exiting through the wall and burning takes place in an elongated flame extending well beyond the open end of the shell.

Most prior blast burner tips have been comparatively unsatisfactory, especially for use in heating shell molds. First, it is desirable that the tips produce a relatively uniform, circular flame pattern for even heating of the molds. The prior nozzles have tended to produce an elongated tapered flame which provides a concentrated spot heating. Secondly, the tips must preferably be capable of operating on variable gas pressures of, for example, from A" (to 30" of water. Prior tips have tended to blow out at pressures above 5 of water or, alternately have utilized extremely small gas orifices which quickly become clogged with dirt from the shell molds. Thirdly, in the prior tips, combustion is not especially uniform because air is aspirated at the outer edges of the tip shell and produced burning of the gas from the outside of the flame into the center.

The present invention overcomes the above-noted problems and provides a blast burner tip or nozzle which provides an extremely uniform flame of a generally cylindrical shape. Because of the arrangement of the gas-air mixture inlet orifices and their relationship to each other and the side walls of the shell, air tends to be aspirated into the center of the flame to produce burning from the center outwardly, as well as, from the outside inwardly. Further, the arrangement permits relatively large diameter orifices to be used while obtaining excellent operational characteristics throughout a wide range of gas pressures.

In accordance with the invention, a blast burner tip is provided which includes a body having an inwardly ex tending generally cylindrical bore of diameter D and a depth L terminating in a transversely extending end wall and defining a combustion chamber. A plurality of relatively uniformly spaced gas inlet ports of diameter D extend through the end wall in a generally circular layout of diameter D which is less than D Each of the ports is outwardly inclined relative to the axis of the bore and arranged to direct gas into impinging relationship with the wall of the bore. The remaining portions of the endwall are imperforate.

In accordance with more limited aspects of the invention D /L is preferably in the range of .8 to 1.2, D /D is preferably in the range of .7 to .85, and D is in the range of .04 inch to .09 inch for burners having a D in the range of to 1".

Accordingly, the primary object of the invention is the provision of a blast burner tip arranged to produce aspiration of air into the center of the flame to provide a more uniform flame and better combustion than prior nozzles.

A further object of the invention is the provision of a burner of the type described which produces a relatively uniform flame pattern.

Still further objects are the provision of a blast burner tip which is simple to produce, capable of operating under a wide range of gas pressures, and self-cleaning in operation.

These and other objects and advantages will become apparent from the following description when read in conjunction with the accompanying drawings wherein:

FIG. 1 is a cross-sectional elevation of a blast burner tip formed in accordance with the preferred embodiment of the invention and showing the tip mounted on a gas pp y P p FIG. 2 is an enlarged view of the tip, partially in section;

FIG. 3 is an exploded pictorial view of the tip; and,

FIG. 4 is an enlarged top view.

Referring more specifically to FIG. 1, the improved blast burner tip is shown as being threadedly mounted on the outlet end of a gas supply pipe 12. This form of mounting is merely exemplary and the tip can, of course, be mounted in a variety of different ways, such as on a gas supply manifold, singly or in groups.

Specifically, as shown, the burner tip comprises a generally cylindrical body 14 formed, for example, from steel, alloy or other suitable material capable of withstanding the temperatures experienced by the nozzle.

Preferably, the exterior of the body is provided with pipe 'threads 15 which extend a substantially distance along the length and provide a convenient manner of mounting the tip. Additionally,the upper or outlet end of the body 14 is provided with wrench flats 17 to facilitate mounting.

Extending axially inwardly of the body 14 a distance L is a uniform diameter bore 16 of diameter D and having a cylindrical side wall 19. In most blast burner tips the bore 16 would have a diameter in the range of We" to 1%. although this can vary substantially. The bore 16 terminates in a transversely extending, generally imperforate end wall 18 which defines the inlet end of the burner. As can be appreciated, wall 18 could be formed integrally with body 14; however, in the embodiment shown, the wall. is formed by a separate discshaped member 18:: which is arranged to be closely received in a bore 22 extending inwardly a short distance from the inlet end of the body and coaxial with bore 16. The member 18a is maintained in position in bore 22 in any convenient manner such as, for example, by having the edge of the bore 22 rolled over as shown at 23.

As previously mentioned, When blast tips are used in shell molding machines it is important that they produce a flame having a generally circular or cylindrical pattern, i.e. a longitudinal cross-section through the flame is rectangular. Additionally, it is important that the tip be, in effect, self-cleaning and be capable of functioning properly throughout a comparatively wide range of gas pressures with good flame retention. The present burner meets these criteria with a unique inlet arrangement.

4 the top edge of the bore as shown in FIGS. 1 and 2. To facilitate this aspiration, the upper edge is preferably rounded or chamfered as shown at 30.

Merely by way of example and not limitation the following chart gives the dimensional relationships for a Specifically, referring to FIGS. 2 and 4, it is seen that range of blast burner nozzles formed in accordance with a plurality of fuel inlet orifices extend inwardly the invention. The dimensions given can be varied but through the end wall 18. The orifices 20 are laid-out in those shown have given preferred results.

D2, D1, L, D3, Dz/Di, Dl/L, Dl/L, Az/Al, inch inch inch inc inch inch inch inch Tip nominal size, inch:

% 3 '2 g5 .55 .052 .814 .74 .91 .663 4 5 .63 .052 .8 .795 .99 .640 M .6 .73 .070 .s .8 1.03 .640 1 .s 1 .9 .086 .s .890 1.11 .642

NOTE: A2=7rD 2/4 Al=1rD l/4 a generally circular pattern of a diameter D The value The invention has been described in great detail suffi- Of 1 is P f y in a range f pp y cient to enable one of ordinary skill in the gas burner to 1.2 with l belng the preferred. Additionally, the value art to make and use the Same of D D 1s preferably in the range of from .7 to .85. Having thus described my invention, I claim:

Variations in the number and size of the or1fices 20 1 A bl tb r r b d b h can take place within limits; however, one of the adas u ne 1P .compnsmg a y mam avvantages of the subject nozzle is that a relatively few mg an mwardly extendmg bore of dlametef' m th6 (4-8), comparative large diameter (.05 to .09") orifices range of to 11/2" and a depth L tefmlnatlng 111 a can be utilized for nozzles in the /8" to 1 /2 size. Even transversely extfinding end Wall, a plurality of relatively with orifices of this size, nozzles formed in accordance uniformly spaced gas inlet ports of diameter D extendwith the invention function with excellent flame retening through said end wall in a generally circular layout tion throughout a range of gas-air mixture pressures of of diameter D which is less than D with D /D in the from 1A" to or 9 Water- It 15 relatlvely lmpor' range of approximately .7 to .85 and D /L being in the tam howeve.r that the orifices can P one range of approximately .7 to .95, each of said inlet ports i dlstance from 3 to 4 tmies 1,161! i being outwardly inclined relative to the axis of said bore s Wlll be noted in FIG. 2, the orifices axes are mclined relative to the axis of bore 16 at an angle B which to d1 rect gas ,lmpmgmg elatlonshlg w1 th the wall is f r bl but which can Vary Within 30 and of sa1d bore, sa1d end wall being otherwise lmperforat e. This produces an impingement of the gas-air jets against 40 The blast burner p as defined in 6131111 1 Wherem the wall 19 of bore 16. With the orifices spaced as dis- D is in the range of .04 inch to .08 inch and D /L is in cussed above, the impingement of the jets against the the range of .8 to 1.2. Wall causes the edges of each individual j to j impinge 3. The blast burner tip as defined in claim 1 wherein the edges of the next adjacent jet. This tends to increase the ports are i d outwardly l i t th i f the efiectlvjness of the f said bore at an angle in the range of 30-60.

AS prevlously mentloned the .Sublect burner .nozzle 4. The blast burner tip as defined in claim 3 wherein produces a flame pattern of relat1vely uniform circular D th f 8 1 18111 i erangeo to 1.2. cross-section as distinct from the usual tapered flames. d fi d 1 3 h The reason for this flame is the result of ambient air be- T blast burmr t1p.as e He 6 mm w erem ing aspirated into the longitudinal center of the nozzle, D3 15 m the range of Inch to as well as, around the circumference. This phenomena can be clearly shown in tests of the burner and is believed References Clted to result from the arrangement of the orifices 20 and UNITED STATE PATENTS the absence of any orifices which direct gas-air mixture into the longitudinal center of the bore. As can be ap- 2210032 8/1940 H685 1 2 preciated, the orifices arrangement provided in combina- 215 15,845 7/1950 Van Den ussc e tion with the above-noted dimensional relationships 2,646,113 7/ 1953 Tavenel' 431-353 X causes the burning gas-air to pass up through the nozzle 3,139,138 6/1964 Bloom 431177 in a somewhat tubular shape. This produces a low pres sure area longitudinal of the bore which causes air to be CARROLL B. DORITY, 111., Primary Examiner aspirated into the center. Thus, the gas-air mixture burns from the center outwardly and from the outside inwardly. The tubular gas-air supply shape within the bore also 239-548 produces a circumferential low pressure zone between the flame and the wall 19. This aspirates air down over 

